This invention relates to a motor/generator provided with a plurality of rotors.
Tokkai-Hei-8-340663 published by the Japanese Patent Office in 1996 discloses a motor/generator having one stator and two rotors. The stator and rotors are disposed co-axially, one rotor being arranged on the inner side of the stator while the other rotor is disposed on the outer side of the stator.
In this motor/generator, the stator is provided with an independent group of coils for each rotor. Two groups of coils respectively drive the rotors by producing two different rotating magnetic fields.
In order to supply power currents of different waveforms to the two groups of coils, the motor/generator has two inverters. Accordingly, the construction of the motor/generator is complicated and the switching loss in the inverters is also large. Furthermore the overlapping disposition of the rotors on the inner and outer sides of the stator results in the stator requiring a cantilever support structure which has low structural stability.
It is therefore an object of this invention to reduce current loss of a motor/generator provided with a plurality of rotors.
It is a further object of this invention to increase the stability of the support for the stator of a motor/generator provided with a plurality of rotors.
In order to achieve the above objects, this invention provides a motor/generator comprising a first rotation shaft, a second rotation shaft, a first rotor, a second rotor, a stator and a current control device.
The first rotor rotates with the first rotation shaft and has a first number of magnetic poles that form a first magnetic field. The second rotation shaft rotates relative to the first rotation shaft and is supported co-axially with the first rotation shaft. The second rotor rotates with the second rotation shaft and has a second number of magnetic poles that form a second magnetic field.
The first number and the second number are different. The first rotor and the second rotor are disposed in series along the first rotation shaft. The stator comprises coils that generate a first rotating magnetic field in synchronism with the first magnetic field by application of a first alternating current, and generate a second rotating magnetic field in synchronism with the second magnetic field by application of a second alternating current. The current control device supplies a composite current comprising the first alternating current and the second alternating current to the coils.
This invention also provides a motor/generator comprising a first rotation shaft, a second rotation shaft, a first rotor, a second rotor, a first stator, a second stator and a current control device.
The first rotor rotates with the first rotation shaft and has a first number of magnetic poles that form a first magnetic field. The second rotation shaft rotates relative to the first rotation shaft. The second rotation shaft and the first rotation shaft have different rotation axes. The second rotor rotates with the second rotation shaft and has a second number of magnetic poles that form a second magnetic field. The first number and the second number are different. The first stator comprises a third number of first coils that generate a first rotating magnetic field in synchronism with the first magnetic field by application of a first alternating current. The second stator comprises a fourth number of second coils that generate a rotating magnetic field in synchronism with second magnetic field by application of a second alternating current. Herein, the third number is equal to the fourth number. The current control device supplies a composite current comprising the first alternating current and the second alternating current to both the first coils and the second coils.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.